Project Summary/Abstract The overall goal of this proposed study is to field test and validate recently developed particulate matter monitors for multiple parameters, including their usability as personal exposure tool for second hand tobacco smoke (SHS). A wide array of symptoms and diseases in both adults and children are associated with SHS exposure, and it has been concluded that there is no safe level of exposure to SHS, a stressor and confounder. The historical decline in smoking rates in the US population has leveled with an estimated 43% of the US population currently exposed to significant levels of SHS, suggesting that understanding the patterns of exposure for SHS, especially for poor children is still critically important. Standard exposure tools all have problems; additional methods, which are objective, quantitative and can assess personal exposure levels and pathways are critically needed. This proposal focuses on novel approaches for assessing personal exposure to SHS that have been built into the miniaturized particulate matter monitors recently developed by teams headed at Columbia University and RTI. Both teams have focused on approaches that provide both real-time data of key PM components, compliance and activity data, as well as collecting filters of sized PM that can be assessed in the lab for SHS by non-destructive optical methods. Prior work has shown that the activity monitors integrated into the RTI and Columbia monitors can predict ventilation rate as a function of time, allowing estimation of potential inhaled dose as an additional method. Our premise is that the advantages of using these two newly-developed air monitors will be that they will provide assessment of complex mixtures of PM while also providing more robust SHS exposure distributions with less exposure misclassification than traditional methods. This proposal brings together two groups from the GEI Chemical Sensor Program and investigators running inner city asthma cohort studies in NYC and Baltimore. Early versions of miniaturized particulate monitors developed by the two groups have been successfully deployed in lab and field tests and development is continuing in the current year, focusing on reductions in size and improvements in ease of use so as to decrease field costs and increase compliance. With this team, our goals will be accomplished via the following specific aims: Aim 1) Assess the usability and acceptability of the miniaturized personal air monitors for cohort studies. Aim 2) Assess the sensitivity and specificity of real time and integrative filter based methods for assessing exposure to second hand smoke and other sources of particulate matter.